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  #46  
Old 08-10-2017, 10:53 AM
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Or, perhaps shine a laser pointer on the center of the screen and see if it is visible in the center of the 3np4.

jr
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  #47  
Old 08-10-2017, 07:50 PM
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Phil Nelson Phil Nelson is offline
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I pulled the chassis and opened the optical box. I thought that the spherical mirror could only be mounted in one way, bolting onto the rear wall of the box. While it doesn't have adjusters as such, now I see that the holes in the box are bigger than its mounting screws, providing some wiggle room:



Large washers go on both sides of the hole, so clearly some sliding back & forth was contemplated.

With all three screws loosened, you can slide the mirror a bit in any direction. Not foreseeing that alignment would be an issue, I have no record of exactly how it was mounted before I removed the mirrors. Nor do I know exactly where it was mounted when it produced the most recent picture, since I didn't know the screws had any leeway until I had loosened them all today.

I don't have a factory jig for aligning all this stuff, so unless someone has a better idea, I'll mark the box with tape tags showing the center of each mounting hole, and try to remount the mirror dead center in all three holes.

Also on my to-do list is checking the angle of the plane mirror to make sure it's exactly 45 degrees, and to ensure that each of the three side clamps is holding it the same distance from the struts (i.e., even if it's lying back exactly 45 degrees, it's not tilting sideways, either).

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
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  #48  
Old 08-11-2017, 10:41 AM
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You need one of these!

http://www.earlytelevision.org/philips_test.html

Perhaps something similar could be fabricated.

jr
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  #49  
Old 08-11-2017, 11:52 PM
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Phil Nelson Phil Nelson is offline
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Wow, that Philips gizmo is clever. It sure would simplify the optical adjustment process, although fabricating one goes far beyond my pay grade.

Meanwhile, I reopened the optical box today. After much fussing & cussing, I readjusted the spherical and 45-degree plane mirrors. Now, the picture is similar to what it was before I pulled those mirrors for resilvering:



I haven't yet done ANY of the multiple mechanical adjustments, so the picture is blurry and the screen geometry isn't perfect. Presumably things can be improved somewhat that way.

It also looks a little bloomy on high-contrast content, as you can see in the animated .GIF. Poor HV regulation? There's no quick/easy way to measure the HV output, as you would in a conventional TV, so this is only a guess.

Speaking of mirrors, I stuck my head up inside the pop-up canopy to inspect the big (final) mirror. Guess what -- it looks bad, similar to the degraded surface on the 45-degree plane mirror. That would explain some of the image weirdness seen in the last photo, which is more than just being out of focus.

Tomorrow . . . .

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Last edited by Phil Nelson; 08-12-2017 at 12:04 AM.
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  #50  
Old 08-12-2017, 12:53 AM
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I may be wrong, but I think that the vertical keystone can be improved by a side to side adjustment of the 45 degree mirror. I would not assume that the 45 degree rails are perfect.

The focus looks fairly uniform, I suspect that moving the CRT foreward or backward will sharpen it quite a bit... perhaps put a dab of lubricant on each of the 3 "fingers" that move the CRT mount so the focus action is smooth.

jr
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  #51  
Old 08-12-2017, 10:58 PM
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Yah, I'm probably not done messing with that plane mirror.

Looking up top, I noticed that the screen's wooden frame is slightly cracked open on one side; thus, that corner of the frame doesn't slide forward all the way when you lock the screen in viewing position. Which means the big mirror is also misaligned.

Note the gap on the right side, between the screen frame and the control panel frame:



I guess these things happen when a fragile, heavy cabinet is trundled around from house to house over the decades :-(

I was planning to remove the canopy anyway, to give the big mirror a close inspection. Now I have two reasons to remove it!

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
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  #52  
Old 08-13-2017, 04:06 PM
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Quote:
Originally Posted by Phil Nelson View Post
Wow, that Philips gizmo is clever. It sure would simplify the optical adjustment process, although fabricating one goes far beyond my pay grade.
Perhaps not... jr crazy idea for the day:

Apply some sort of pattern to the face of the tube, transfer letters, decal, felt tip pen, whatever you have handy.



Install tube in the box and illuminate face with bright flashlight. Fenix MC-10 shown here.



View on screen approximately 31 inches from the corrector plate... Align for best image.



Of course, the set up could be much better, but this was just a quick n dirty experiment to illustrate the concept, using a washing machine instead of a flat level table as an "optical bench" and a clipboard with white piece of paper instead of a proper screen.

jr
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  #53  
Old 08-13-2017, 07:29 PM
old_coot88 old_coot88 is offline
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Phil you are da man when it comes to MacGyvering.
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  #54  
Old 08-13-2017, 09:52 PM
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Yeah, something like that flashlight setup might work for aligning the optical box mirrors.

Meanwhile, I managed to extract the canopy with its final mirror & screen. (Hint: this process is a pain; don't do it without a good reason.)



The final mirror doesn't look that bad from a distance:



The closer you get, the worse it looks, showing the same flaws as the 45-degree mirror in the optical box. This isn't dirt; I cleaned the mirror, with no change in the degraded areas:



Yes, this frame corner has popped loose (and so has the adjacent one). This rail would fall out completely if the screen mount wasn't holding it from behind:



I'll pull the mirror from the canopy and send it off for recoating. That will take about a month, and during that time I can do cabinet refinishing & repair (it also has a broken leg). Maybe some MacGyver experiments, too!

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html
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  #55  
Old 08-13-2017, 10:27 PM
Crist Rigott Crist Rigott is online now
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Hang in there. If anybody can get this thing right you'll be the one.
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  #56  
Old 08-13-2017, 11:44 PM
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Thanks for the encouragement. I bought this set thinking that a projection TV might be an interesting new challenge. I got that wish, and then some!

Phil Nelson
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